Air control means for combustion apparatus



Feb. 22, 1938. c, SCHOLL 2,109,239

AIR CONTROL MEANS FOR COMBUSTION APPARATUS Filed Oct. 19, 1935 2 Sheets-Sheet 1 IWENTOEI CV0? Sofia/2 C. SCHOLL Feb; 22, 1938;

UTSTION APPARATUS AfR CONTROL MEANS FOR COMB Filed Oct. 19, 1935 2 Sheets-Sheet 2 (ATTOWJS Patented p.512, i938 i 2,109,239

UNITED STATES PATENT OFFICE i Am. common-trams FOR. COMBUSTION APPARATUS Clark Scholl, Springfield, Ohio, assignor to The Steel Products Engineering Company, $pringfield, Ohio, a corporation of Ohio Application October 19, 1935, Serial No. 45,776 13 Claims, (01. 230-114) The present invention relates to improvements thereby permitting the fuel bed to build up to in automatic air control means forv combustion the proper depth, and preventing substantial apparatus, and has particular reference to a combustion losses because of an undue volume new and improved automatic damper for controlof excess air.

ling the supply of air under pressure to the fuel A more specific object resides in the provision 5 bed of a furnace, as for-example in the retort in an air blower of a novel rotary inlet damper of an underfeed coal stoker. automatically adjustable in accordance with the It is well recognized that a proper ratio of varying height of a liquid which is responsive fuel ,and finely dispersed air must be maintained in level to the differential between the static in order to obtain eflicient and satisfactory compressure of the air delivered by the blower and 10' bustion. Such ratio is diflicult to obtain in the pressure of the atmosphere.

stokers with forced draft because of variations A general object resides in the provision of a in operating conditions influencing the amount of new and improved damper of the foregoing charair supplied to the combustion zone. In one acter which is simple and inexpensive in concommon type of underfeed stoker, fuel is fed struction, and sensitive, accurate and reliable in 15 through a duct into the bottom of a retort to operation.

form a fuel bed, and air for combustion is sup- Further objects and advantages will become plied under pressure by a fan or blower through apparent as the description proceeds. a duct to a plenum chamber, and then through In the accompanying drawings, Figure 1 is a tuyere openings into the bed. When the fuel bed plan view of an underfeed stoker provided with 20 is heavy and dense, the static pressure of the air automatic air supply means embodying the feawill be relatively high, and at times may reach tures of my invention. the maximum that the blower can develop. Con- Fig. 2 is a fragmentary vertical sectional view versely, when the fuel bed is thin and porous, its on an enlarged scale taken along line 2-2 of Fig.

resistance to the passage of air is greatly re- 1, and illustrating the automatic air supply 25 duced, and hence the static pressure of the air means.

may be very low. The volume of air delivered Fig.3 is an axial sectional view of the blower by the blower varies inversely with the static taken along line 3-3 of Fig. 2. pressure in the air passages. Thus, when the Fig. 4 is a horizontal sectional view taken fuel bed is heavy, and the volume of air should along line 4-4 of Fig. 2. 30

be correspondingly high, the actual volume of air Fig. 5 is a vertical sectional view of a modisupplied is relatively low. When the fuel bed is fied form of the invention. light, and a relatively small amount of air is re- Referring more particularly to the drawings,

quired, the amount of air actually supplied may the underfeed stoker disclosed in Fig. 1 has a be considerably in excess of that required for burner l0 comprising an upwardly opening fire 35 combustion, thus resulting in serious heat losses. pot or retort II, a plenum chamber l2 surround- 'I'he condition of the fuel bed is determined by ing the pot, and tuyres i3 opening from the the kind of fuel that is used, the rate of fuel chamber to the top of the pot. Solid fuel, such feed, and the rate of combustion. for example as coal, is fed by a conveyer l4 from 40 One of the primary objects of the present a hopper I5 through a duct l6 into the bottom 40 invention resides in the provision of novel means of the fire pot l l to form a fuel bed. Air under for supplying air under pressure automatically pressure is supplied by a fan or blower I1 through in accordance with the conditions of the fuel a duct It to the plenum'chamber l2 for disbed, thereby avoiding the inconvenience of and charge through the tuyeres 13 into the top pornecessity for manual supervision and adjusttion of the fuel bed. The conveyer Hand blower 45 ment, and the undesirable consequences of failure I! are driven in timed relation through a variable to make proper adjustments. speed mechanism Hi from an electric motor 20.

Another object is to provide an automatic Preferably, the blower H, the variable speed damper for the air supply means which is responmechanism l9, and the motor 20 are rigidly .sive to the static pressure of the air passing tov mounted on the base of the hopper i5. 50

the fuel bed so that when the static pressure 'The blower H, which constitutes the air supincreases, the damper is moved correspondingly ply means, may be of any suitable character, and toward open position, and when the static presis herein shown as of the rotary type. More parsure drops, the damper is moved correspondingly ticularly, the blower l1 comprises a generally toward closed position to restrict the flow of air, cylindrical housing 2| which has a tangential iii outlet 22 connected to the duct i 8, and which is formed in one side wall with a circular opening 23. A rotor or fan wheel 24 is fixed ona shaft 25 for rotation within the housing 2|, and comprises a plurality of annularly arranged peripheral vanes 28 defining a hollow interior space 21 open at one side and closed at the other side. The shaft 25 is driven by the motor 28. Attached in fixed position to the housing 2| about the front opening 23 is a ring 28 having an inwardly tapering conical flange 28 for directing air to the interior space of the rotor 24.

An important feature of the present invention resides in the provision of novel air control means, preferably in the form of a damper, which serves to control the volume of air supplied through the duct l8 to the fuel bed, and which is automatically adjustable in accordance with changes in the static pressure of the air. The damper may be of any desired form or type, and

may be located in any suitable position of control inthe air supply system. In the preferred form of the invention, the air supply is controlled at the inlet of the blower I! by a damper 30 of the rotary type. Preferably, the damper 33 comprises a fixed plate 3| integral with the ring 28, which constitutes a rim therefor, and a flat circular rotary plate 32 disposed against the outer face of the plate.3l. The fixed plate 3| is formed with an inwardly extending axial hub 33 supporting a fixed shaft 34 on the outer end of which the plate 32 is suitably joumaled. Also secured to the shaft 34 within the wheel 24 is a generally conical deflector 35 for directing the incoming air toward the vanes 26. The fixed and movable plates 3| and 32 are formed respectively with radial uniformly peripherally spaced openings 36 and 31 adapted to be moved progressively into different degrees of communication between zero and full registration.

The damper plate 32 is rotatably adjustable to adjust the effective air inlet and hence the air intake of the blower IT in accordance with variations in the static. pressure of the air supplied to the fuel bed. In the preferred embodiment of the invention, this is accomplished through the medium of a liquid 38 which tends to seek different levels in accordance with changes in the differential between the static pressure of the air delivered by the blower l1 and atmospheric pressure, and which actuates an adiusting member 38 operatively connected to the damper plate 32. The liquid 38 is placed in a reservoir 40 which is divided by apartition 4! at the top into two chambers 42 and 43 intercom'municating under the liquid level. One chamber 42 is sealed from the atmosphere, and is connected above the liquid level through a passage 44 with the interior of the duct l8. The other chamber 43, although substantially closed by a cover 45, is open at the top to the atmosphere. When the'stoker is idle, and atmospheric pressure prevails in the duct i8, the liquid 38 will assume the same level in both chambers 42 and 43 as indicated at 48. However, when the stoker is operating, the static pressure in the duct l8 will exceed atmospheric pressure more or less, and will depress the liquid in the chamber 42 according y. for example to the level 41, and thereby will cause a corresponding rise of the liquid in the chamber 43 to the level 48. The adjusting member 39 is movable in response to the variations in liquid level.

In Fig. 2, the reservoir 40 is elongated and rectangular, and extends along and is directly secured to one side of the duct II. The passage 44 times.

is defined by registering openings in the contacting walls of the duct I8 and the reservoir 40. The

chambers 42 .and 43 preferably are disposed in opposite ends of" the reservoir 40, and hence are float in the chamber 43, which is of greater,

height and of less horizontal area than the chamber 42, and has a vertical connecting rod or stem extending upwardly loosely through an opening 5| in the cover 45. Pivotally connected at one end to the upper end of the rod 50 is a lever 52. The other end of the lever 52 is connected through a swinging link 53 to the damper plate 32. Intermediate its ends, the lever 52 is mounted for pivotal movement on a horizontal axis between two centers 54 adjustably secured in two upstanding arms 55 of a bifurcated bracket 56 rigidly mounted on one end of the reservoir 40.

It will be seen that if the fuel bed is light and porous, the static pressure in the duct I8 will be low. As a result, the float 39 will be'lowered to restrict the flow of air through the damper 38. Hence, the supply of I air to the fuel bed, although adequate, will be cut down, thereby giving the fuel bed a chance to build up to the proper depth, and preventing an undue volume of excess air from passing through the fuel bed and diluting the products of combustion. As the fuel bed increases in depth and the holes fill up, the static pressure increases, thereby increasing the damper opening. Thus, the correct damper adjustment is automatically maintained at all The adjustment is substantially in accordance with the condition of the fuelbed, and takes into account the kind of fuel burned, the

rate of feed and the rate of combustion in so far by the flange 28 so that there will be no restric- I tion in the flow of the air by the damper 30 when the latter is wide open.

In the modification shown in Fig. 5, the automatic' damper controls the fiow of air from the blower I! rather than the air entering the blower. The damper comprises a plate 32 mounted within the duct l3 for pivotal movement about a horizontal axis 34" into different angular positions relative to the path of air flow. The operating mechanism for the pivotal damper plate 32*, except for minor difl'erences hereinafter described, is closely similar to that for the rotary damper plate 32, and'hence like parts thereof are designated bythe same reference numerals plus the subscript a.

In this form, the reservoir 40 is mounted on the top of the 'duct l8, and the passage 44* opens from the duct upwardly through one end of the chamber 42' to the'top of the liquid 38-. The cover 45' for the chamber 43' has a central cylindrical upstanding dome 51 formed with a series of peripherally spaced openings 5| to the atmosphere. The damper plate 32 is operable by a rod 58 to which it is pivotally connected at one side of the axis 34', and which extends upwardly from the duct l8 through a vertical tube 59 encircled by the annular fioat 39-. The lower end of the tube 53 is threaded into a flanged opening 53 in the bottom of the chamber 43" and in registration with an opening 5| inthe top wall of the 62, fixed centrally on the top of the float 39 and sealed internally from the chamber 43, is pivotally connected to the upper end of the rod 58, and is adapted to telescope loosely onto the tube 59 or into the dome 51.

I claim as my invention: 1. An automatic damper for forced-draftstokers comprising, in combination with a rotary blower having a discharge duct and an axial atmospheric air inlet, a fixed damper plate extending across said inlet, a rotary damper plate mounted in cooperative relation against said fixed damper plate, said plates having air inlet openings movable respectively into different degrees of registration to define the efiective air inlet area, and means located outside of said duct for automatically adjusting said rotary plateto increase and decrease said air inlet area respectively in accordance with increases and decreases in the static pressure of the air discharged from said blower.

2. An automatic damper for forced-draft stokers comprising, in combination with a rotary blower having a discharge duct and having an air inlet, a fixed damper member extending across said inlet, a rotary damper member mounted in cooperative relation against said fixed damper member, said members being fiat and having air inlet openings movable respectively into difierent degrees of registration to define the efiective air inlet area, a stationary reservoir adapted to contain a liquid varying in level in accordance with changes in the static pressure of the air flowing through said duct, and means operable in response to variations in the level of said liquid for automatically adjusting said rotary member.

I 3. An automatic damper for forced draft stokers comprising, in combination with a rotary blower having a peripheral discharge duct and having an air inlet in one side, a fixed damper member for said inlet, a rotary damper member mounted in cooperative relation with said fixed damper member, said members having air inlet openings movable respectively into difierent'degrees of registration to define the eflective air inlet area, a stationary reservoir having two liq- Y uid chambers in intercommunication below the liquid level, one of said chambers being closed to the atmosphere and being in communication above the liquid level with said duct, the other of said chambers being open to the atmosphere, and means operable in response to variations in liquid level in one of said chambers for adjusting said damper automatically in accordance with variations in the static pressure of the air in said duct.

4. An automatic damper for forced draft stokers comprising, in combination with a rotary blower having a hollow propeller and having a casing with a peripheral discharge duct and an air inlet opening in one side, a fixed damper plate secured to said casing across said inlet and having a conical flange for directing air into said propeller, a rotary damper plate mounted in cooperative relation against said fixed damper plate, said plates having air inlet openings movable respectively into different degrees of registration to define the efiective air inlet area, the aggregate area of the openings in each damper plate being no less than the area circumscribed by said flange, and means out of the path of air fiow through said duct and adjustable in response to variations solely in the static pressure of the air in said duct for adjusting said rotary plate to effect a proportionate adjustment of said inlet area.

5. An automatic damper for forced draft stokers.

tending across said inlet, a rotary damper plate mounted in cooperative relation against said openings movable respectively into difierent degrees of registration to define the efiective air inlet area, means defining two chambers con-' fixed damper plate, said plates having air inlet taining a liquid in intercommunication below.

the liquid level, one chamber being closed to the atmosphere and being connected above the liquid level to said duct, the other chamber being open above the liquid level to the atmosphere, a float on the liquid in said other chamber, and means operatively connecting said float to said rotary plate to control said air inlet area in accordance with changes in the static pressure in said duct to increase the air flow upon an increase in static pressure and to reduce the air flow upon a decrease in static pressure.

6. An automatic damper for forced draft stokers comprising, in combination with a blower having a discharge duct and having an air inlet, a fixed damper member for said inlet, a rotary damper member mountedin cooperative relation with said fixed damper member, said members having air inlet openings movable respectively into difierent degrees of registration to define the effective air inlet area, means defining two chambers containing a liquid in intercommunication below the liquid level, one chamber being relatively large and shallow, being closed to the atmosphere and being connected above the liquid level to said duct, the other chamber being relatively small and deep and being under a substantially constant pressure above the liquid level, a fioat on the liquid in said other chamber and spaced from the walls thereof, and movement multiplying means operatively connecting said float to said rotary member to control said air inlet area in accordance with changes in the static pressure in said duct.

7. An automatic damper for forced-draft stokers comprising, in combination with a forced draft supply means having a discharge air-flow duct and an air inlet, a rotary damper for adjusting the effective area of the air inlet, a liquid reservoir having a partition defining two liquid chambers intercommunicating below the liquid level, one of said chambers being closed to the atmosphere and in communication above the l quid level with said duct, the other of said chambers being open above the liquid level to the atmosphere, a fioat in said other chamber, a lever pivotally mounted intermediate its ends on said reservoir and having a link connection at one end with said float and a link connection at the other end with said damper, whereby vertical movement of said fioat will efiect a proportionate angular adjustment of said damper.

8. An automatic damper for forced draft stok- ,ers comprising, in combination with a blower having a discharge duct and an air inlet, a damper for adjusting the effective area of the air inlet, a liquid reservoir having a partition defining two rectangular liquid chambers juxtaposed end to end and intercommunicating below the liquid level, one of said chambers being relatively large and closed to the atmosphere and in communication above the liquid level with said duct at the discharge side of said damper, a float in the other chamber which is relatively small and open above the liquid level to the atmosphere, and movement multiplying means operatively connecting said damper and said float for synchronous movement, whereby vertical movement of saidfloat in response to varying liquid levels will efiecta proportionate adjustment of said damper.

9. An automatic damper comprising, in combination with an air-flow passage, an adjustable damper for controlling the volume oi air flowing through said passage, a liquid reservoir having two liquid chambers inte'rcommunicating below the liquid level, one of said chambers being closed to the atmosphere and in communication above the liquid level with said passage at the outlet side of said damper, the other of said chambers being open above the liquid level to the atmosphere, a float in one of said chambers, a lever having a fixed fulcrum and having pivotal connections with said float and said damper whereby movement of said float in response to varying;

liquid levels will efl'ect ,a proportionate adjustment of said damper.

10. An automatic damper comprising, in combination with an air flow passage, an adjustable damper for controlling the volume of air flowing throughsaid passage, a reservoir having two liq uid chambers of unequal height and of unequal horizontal areas in intercommunication below the liquid level, the chamber or larger area being closed to the atmosphere and in communication above the liquid level with said passage at the outlet side of said damper, and a float in the chamber of smaller area operable in response to variations in liquid level for adjusting said damper automatically in accordance with variations in multiplying means to said damper to effect a proportionate variation in the air inlet area.

12. An automatic damper comprising, in combination with an air duct and means for supplying air under pressure to said duct, a damper pivotally mounted in said duct, a liquid reservoir mounted on said duct and having a partition defining two liquid chambers in intercommunication below the liquid level, one of said chambers being closed to the atmosphere and being in communication above the liquid level with the interior of said duct at the discharge side of said damper, the other or said chambers being open to the atmosphere, a tube communicating with said duct and extending outwardly into said other chamber to a point above the liquid level,

an annular float mounted on the liquid in said other chamber and encircling said tube, a cap on said float telescoping with and substantially sealing said tube fromv the atmosphere, and a pivotal link connection between said cap and said damper extending through said tube, whereby said damper will be moved toward open position as said float rises in response to an increase in static pressure in said duct.

13. An automatic damper comprising, in combination with an air duct and means for supply- I ing air under pressure to said duct, an adjustable damper in said duct, a liquid reservoir mounted over said duct and having two liquid chambers in intercommunication below the liquid level, one of said chambers being closedto the atmosphere and being in communication above the liquid level with the interior of said duct, the other of said chambers being open to the atmosphere, a tube communicating with said duct and extending into said otherv chamber to a point above the liquid level, an annular float mounted in said other chamber and encircling said tube, and a connection between said damper and said float extending through said tube, whereby said damper will be adjusted synchronously with the vertical movement of said float in response to variations in the static pressure in said duct.

CLARK SCHOLL. 

